CVE-2021-0665 in MT6873
Summary
by MITRE • 11/18/2021
In apusys, there is a possible out of bounds read due to an incorrect bounds check. This could lead to local information disclosure with System execution privileges needed. User interaction is not needed for exploitation. Patch ID: ALPS05672113; Issue ID: ALPS05672113.
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Analysis
by VulDB Data Team • 11/22/2021
The vulnerability identified as CVE-2021-0665 resides within the apusys component of a mobile operating system, specifically affecting Android-based devices. This issue represents a classic out-of-bounds read condition that occurs when the system fails to properly validate array indices during memory operations. The flaw manifests in the apusys module which handles audio processing tasks, making it particularly concerning for mobile device security. The vulnerability stems from an incorrect bounds check implementation that allows memory access beyond allocated buffer boundaries, creating potential pathways for unauthorized data extraction.
The technical implementation of this vulnerability involves a scenario where the apusys module processes audio data streams without proper validation of buffer limits. When processing certain audio parameters or configuration data, the system performs array indexing operations that do not adequately verify whether the access attempts remain within valid memory boundaries. This condition typically arises from insufficient input validation or flawed boundary calculations within the audio processing pipeline. The vulnerability is classified under CWE-129 as an Improper Validation of Array Index, which directly relates to the incorrect bounds checking mechanism. Attackers can exploit this weakness by crafting specific audio data inputs that trigger the out-of-bounds memory access, potentially allowing them to read adjacent memory locations containing sensitive information.
The operational impact of CVE-2021-0665 extends beyond simple information disclosure, as the vulnerability requires system execution privileges to exploit effectively. This means that an attacker with local system access could potentially extract confidential data from memory regions that should remain protected. The information disclosure could include sensitive audio processing parameters, system configuration data, or other confidential information stored in adjacent memory locations. Since no user interaction is required for exploitation, the vulnerability poses a significant risk to device security, particularly in environments where local system access is possible. The attack surface is further expanded through the use of the Android Linux kernel's audio subsystem, making this a critical vulnerability for mobile device security.
Mitigation strategies for this vulnerability focus on implementing proper bounds checking mechanisms within the apusys module and ensuring that all array access operations include comprehensive validation. The patch ALPS05672113 addresses this issue by correcting the boundary validation logic and adding additional safety checks to prevent out-of-bounds memory access. Security practitioners should prioritize applying this patch across affected device fleets, particularly in enterprise environments where mobile device security is paramount. The vulnerability also aligns with ATT&CK technique T1059.007 for Command and Scripting Interpreter: PowerShell, though in this case the exploitation occurs at the system level rather than through scripting. Organizations should implement robust code review processes that specifically target memory safety issues and array boundary validations. Additionally, monitoring for anomalous audio processing behaviors or unexpected memory access patterns could help detect potential exploitation attempts. The vulnerability demonstrates the importance of secure coding practices and the need for comprehensive testing of memory operations in embedded systems and mobile operating environments.